JP2004168057A - Fluorine composite resin film and solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorine composite resin film which can keep a light transmission factor outside for a long period with the capability of a surface stain-resistance brought about by a hydrophilic surface. <P>SOLUTION: The fluorine composite resin film is formed by laminating an acrylic film having a refractive index higher than that of a transparent fluorine film on the fluorine film and laminating one more layers of a transparent resin layer on the acrylic film surface. The transparent resin layer of the uppermost surface contains a binder composed of condensate products of silicone compounds. The resin layer is formed by a coating dried film whose surface droplets contact angle is 40° or less. The refractive index of the dried film of the utmost surface is lower than that of the transparent resin layer located just under the film or the acrylic film. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a surface antifouling fluorine-based composite resin film, and more particularly to a surface antifouling solar cell using the fluorine-based composite resin film.

  A cured film of a coating material containing an optical semiconductor (so-called photocatalyst) exhibits superhydrophilicity on the surface and is effective in preventing soiling of outdoor structures, particularly in maintaining light transmittance or light reflectance of a transparent member. Is known (for example, refer to Patent Document 1 and the like).

However, since TiO _2, which is a typical optical semiconductor substance, is a high refractive index material, its cured film becomes a high refractive film. When such a cured film is formed on a transparent member, the transparent member originally has 1% to 5% lower than that of the single-sided coating, and even if the transmittance is maintained due to the antifouling effect against outdoor contaminants, the initial transmission is achieved by including the optical semiconductor. The reduced rate is disadvantageous and requires long-term transmittance data for adoption. In addition, since the optical semiconductor has a function of decomposing organic substances, if it is directly coated on an organic substrate such as polycarbonate, an acrylic resin, or a fluororesin, the organic substrate may be decomposed or whitened by the action of the optical semiconductor. Therefore, it is necessary to provide a barrier layer made of a silicone resin between the organic substrate and the coating film containing the optical semiconductor, and as a result, the transmittance is further reduced. The same is a problem because a reflective plate provided with a reflective film lowers the initial reflectance.

  On the other hand, it is common practice to laminate a high-refractive film and a low-refractive film on the surface of a transparent member, for example, to prevent reflection on the display surface. An antireflection film is used in which a liquid coating material is applied to a representative transparent organic film and a high refractive layer and a low refractive layer are laminated. The antireflection ability of this antireflection film means that the transmittance is simultaneously increased (for example, see Patent Document 2).

However, in this antireflection film, the low refractive index layer on the outermost surface is generally made of a fluororesin-based material, but is a fluororesin-based material formed by a coating method. It does not have outdoor durability for 30 years. Therefore, there is a problem that the antireflection film for a display as described above cannot be used outdoors. Further, since the surface of the fluororesin material is generally water-repellent, dirt easily accumulates on the surface outdoors, and there is also a problem that the dirt tends to decrease the transmittance or the reflectance in a short period of time.
JP-A-11-179835 JP-A-2000-17099

  The present invention is to solve the above problems, and to provide a fluorine-based composite resin film capable of maintaining a light transmittance outdoors for a long period of time by a stain resistance function due to hydrophilicity of the surface. It is another object of the present invention to provide a solar cell capable of improving power generation efficiency.

  The fluorine-based composite resin film according to claim 1 of the present invention has an acrylic film having a higher refractive index than the fluorine-based film laminated on the surface of the transparent fluorine-based film, and one or more layers on the surface of the acrylic film. In a fluorine-based composite resin film formed by laminating a transparent resin layer of the above, the outermost transparent resin layer is formed from a coating dry film having a condensate of a silicone compound as a binder component, and a surface water droplet contact angle of 40 ° or less. While being formed, the refractive index of the outermost dried film is lower than the refractive index of the transparent resin layer or acrylic film located immediately below.

  A second aspect of the present invention is characterized in that, in the first aspect, the transparent resin layer immediately below the outermost dry film is a thermosetting hard coat resin layer.

  According to a third aspect of the present invention, in the first or second aspect, at least a part of the transparent resin layer is formed having a light diffusing means.

  According to a fourth aspect of the present invention, in the third aspect, the light diffusing means is formed of inorganic particles having an ultraviolet absorbing function.

  According to a fifth aspect of the present invention, in the fourth aspect, the inorganic particles are metal oxides.

  The invention of claim 6 is characterized in that the fluorine-based composite resin film according to any one of claims 1 to 5 is provided on the outermost surface of a solar cell module.

  According to the invention of claim 1, the surface can be formed to be hydrophilic by using a condensate of a silicone compound as a binder component without using an optical semiconductor, and the light transmittance is improved by the stain resistance function due to the hydrophilicity of the surface. It can be maintained outdoors for a long time. In addition, since an acrylic film having a higher refractive index than the fluorine-based film is laminated on the surface of the fluorine-based film, the transmittance is improved even with a dry coating having a higher refractive index than when directly formed on the fluorine-based film. This makes it possible to increase the degree of freedom in designing a coating material composition for forming a dry film.

  According to the invention of claim 2, the weather resistance of the fluorine-based composite resin film can be enhanced.

  According to the third aspect of the present invention, the transmittance can be increased by diffusing the reflected light.

  Further, according to the invention of claim 4, it is possible to simultaneously provide the ultraviolet light absorbing function together with the light diffusing function.

  According to the invention of claim 5, the weather resistance of the fluorine-based composite resin film can be improved.

  According to the invention of claim 6, it is possible to prevent the surface of the solar cell module from being stained and to reduce the light transmittance, thereby improving the power generation efficiency. Moreover, the fluorine-based composite resin film is thin and lightweight, and can reduce the weight burden when the solar cell is installed on the roof of a house or the like.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The fluorine-based composite resin film according to the present invention, a transparent fluorine-based film on the surface, a laminate of an acrylic film having a higher refractive index than the fluorine-based film as a resin film substrate, the acrylic film of the resin film substrate The film is obtained by coating the surface of a film with a coating material composition containing a condensate of a silicone compound as a binder component to form a dried film, and forming the outermost transparent resin layer with the dried film.

  In the dried film formed of the above-mentioned condensate of the silicone compound (matrix forming material) formed in the present invention, the matrix forming material has a property of forming a porous matrix (binder). Here, the property of forming a porous matrix means that a liquid mixture obtained by dissolving a matrix forming material in a suitable liquid solvent in which the matrix forming material can be dissolved (eg, water, an organic solvent, etc.) is used as a base material. It means that a film-like material obtained by drying a coating film formed by coating becomes a porous body containing fine voids. The form of the void is not particularly limited, and may be independent like closed cells or connected like open cells. The shape of the void is not particularly limited, and may be, for example, spherical or elongated. In the film formed by applying and drying the coating material composition, when fine particles are present in addition to the matrix forming material, when there is a void at the boundary between the matrix and the fine particles, or between fine particles. When there are voids at the boundary of the matrix, these voids are also substantially the same as the fine voids that constitute the porosity of the matrix.

  As described above, the dried film formed using the coating material composition is composed of a porous matrix, and the matrix acting as a binder contains a large number of fine voids therein. The specific gravity is smaller than the true specific gravity of the material constituting the matrix itself (that is, the material when there are substantially no voids). The ratio of the apparent specific gravity of the matrix to the true specific gravity of the matrix (apparent specific gravity / true specific gravity) is preferably 0.90 or less, more preferably 0.75 or less. Note that, when the coating film includes voids due to the presence of the fine particles, the ratio is a value calculated including the volume of such voids.

  Upon drying of the coating film described above, the matrix-forming material may or may not chemically change while the matrix-forming material is converted to a matrix. Such a chemical change may be, for example, a change in the matrix forming material resulting from a hydrolysis reaction and a subsequent condensation reaction. Even if it does not chemically change, the structure of the matrix forming material changes from a state of being dissolved in a liquid to a state of being porous. Here, the drying is a treatment for preventing a liquid component of a coating film formed by applying the coating material composition from remaining substantially so that a solid coating film remains. May be.

  The mechanism by which the matrix forming material converts the porous matrix upon drying may be any suitable one. For example, in the process of drying a coating film of a liquid mixture containing a matrix forming material to obtain a film, a mechanism in which the film itself has a porous structure due to a chemical change of the matrix forming material can be employed. Specifically, a matrix inherently having a porous structure can be formed due to crosslinking and / or condensation of the matrix forming material. In another embodiment, a mechanism can be adopted in which after the liquid component is removed from the coating film of the liquid mixture containing the matrix forming material, a region previously occupied by the liquid component remains as a void. Furthermore, a part of the matrix forming material contains a functional group that is relatively easily decomposed by thermal decomposition, and the functional group is thermally decomposed by heat drying after forming a dry film, and a region previously occupied by the functional group remains as a void. Mechanisms can also be employed. Furthermore, a method of controlling the molecular structure of the matrix forming material in a liquid state (for example, controlling the ratio of three-dimensional crosslinking / two-dimensional crosslinking, molecular weight, etc.) can be adopted. The more the two-dimensional crosslinks or the lower the molecular weight, the more the dried film tends to be more porous.

  In the present invention, the matrix formed from the matrix forming material needs to be a silicone resin (silica resin) or the like from the viewpoint of weather resistance.

  In one embodiment of the coating material composition used in the present invention, the silicone compound that can be used as the matrix forming material is a silicon compound having a siloxane bond (this is referred to as “silicon compound (1)”) or a film-like compound. In the process of forming the product (dry film), it is a silicon compound (this is referred to as “silicon compound (2)”) that can newly introduce a siloxane bond. The latter silicon compound (2) may already have a siloxane bond. These silicon compounds include organic silicon compounds (that is, silicon compounds having an organic group), silicon halide compounds (for example, silicon compounds containing halogen such as chlorine and fluorine), and organic silicon halide compounds (that is, organic group). And a silicon compound containing halogen).

  When the matrix forming material of the coating material composition is a silicon compound (2) capable of newly providing a siloxane bond, at least two of the groups selected from a hydrolyzable substituent and a hydroxyl group are bonded to the same or different silicon atoms. It is preferably a silicon compound. These at least two groups may be the same or different. The hydrolyzable substituent is hydrolyzed in the presence of water to form a compound having a hydroxyl group (silanol compound). Therefore, a silicon compound in which at least two of the groups selected from the hydrolyzable substituents and the hydroxyl groups are bonded to the same or different silicon atoms, in the presence of water, the group selected from the hydrolyzable substituents and the hydroxyl group. Condensation with the same or another type of silicon compound in which at least two are bonded to the same or different silicon atoms results in a new siloxane bond.

  In another embodiment of the coating material composition used in the present invention, the silicone compound that can be used as the matrix forming material has the following general formula (1):

(Wherein, substituents X ¹ , X ² , X ³ and X ⁴ are represented by hydrogen, halogen (eg, chlorine, fluorine, etc.), a monovalent hydrocarbon group, OR (R is a monovalent hydrocarbon group)) Selected from the group consisting of an alkoxy group and a hydroxyl group represented by OH, which may be different from each other, partially different from each other, or the same as at least ^{one of} X ^{1 to} X ⁴ . Two are groups selected from an alkoxy group and a hydroxyl group, respectively.)
(This is referred to as “silane compound (1)”). This silane compound (1) corresponds to the silicon compound (2) and has at least two, preferably three, and more preferably four identical or different alkoxyl groups and / or hydroxyl groups. The matrix forming material may be one in which at least one alkoxyl group of the silane compound (1) is hydrolyzed.

  In still another embodiment, the silicone compound as a matrix-forming material is a siloxane compound or a siloxane compound formed by condensing one or more of the silane compounds (1) after hydrolyzing, if hydrolyzable. A polysiloxane compound (the siloxane compound and the polysiloxane compound are collectively referred to as “(poly) siloxane compound (1)”). The polysiloxane compound means a compound having two or more siloxane bonds. This (poly) siloxane compound (1) corresponds to the silicon compound (1). The (poly) siloxane compound (1) preferably has at least two alkoxyl groups and / or hydroxyl groups as substituents (such a (poly) siloxane compound is referred to as a “(poly) siloxane compound (2)”). In this case, the (poly) siloxane compound (2) already has a siloxane bond, but corresponds to the silicon compound (2).

  When the silane compound (1) and the (poly) siloxane compound (2) have an alkoxyl group, they may have a hydroxyl group generated by hydrolysis of the alkoxyl group. As a result, the silane compound (1) and the (poly) siloxane compound (2) can be at least partially condensed and cross-linked to form a porous matrix when the coating material composition is applied and dried. . Therefore, at the time of this condensation, not all the generated hydroxyl groups are involved in the condensation, and generally, a part of the hydroxyl groups remains as it is. Incidentally, the (poly) siloxane compound (1) can form a porous matrix when the coating material composition is applied and dried even if it has no alkoxy group and / or hydroxyl group substituent. .

  As described above, the silane compound (1) and the (poly) siloxane compound (2) are cross-linked to form a porous matrix. However, when the substituent is a hydroxyl group or the substituent is an alkoxy group, it is hydrolyzed. The hydroxyl group generated by the crosslinking causes cross-linking due to condensation between silicon compounds, and the one remaining without participating in the cross-linking can function as a hydrophilic group to improve adhesion to a coating substrate or the like. And the film is hardly charged.

  Such a silane compound (1) preferably has a molecular weight of 40 to 300, and more preferably 100 to 200. In the case where the (poly) siloxane compound (1) and the (poly) siloxane compound (2) are required to have a mechanical strength of a dry film, the weight average molecular weight thereof is preferably about 200 to 2,000. More preferably, it is で 1200. When the molecular weight is in this range, the strength of the dried film tends to increase and the porosity of the matrix tends to increase. When the (poly) siloxane compound (1) and the (poly) siloxane compound (2) do not require a mechanical strength in the dry film, the weight average molecular weight is preferably about 2,000 or more, preferably 5,000 or more. More preferably, there is. When the molecular weight is in this range, the hydrolysis reaction proceeds more, and there is almost no unreacted alkoxy group, and the dry film tends to have a lower refractive index.

In one preferred embodiment of the coating material composition used in the present invention, the silicone compound that can be used as the matrix forming material is represented by SiX ₄ (X is a hydrolyzable monovalent organic substituent, for example, an alkoxyl group). Is a tetrafunctional hydrolyzable organosilane. This tetrafunctional hydrolyzable organosilane is included in the silane compound (1).

In another preferable embodiment of the coating material composition used in the present invention, the silicone compound that can be used as the matrix forming material is represented by SiX ₄ (X is a hydrolyzable organic substituent, for example, an alkoxy group). A compound having a siloxane bond formed by condensation of a partial hydrolyzate and / or a complete hydrolyzate of a tetrafunctional hydrolyzable organosilane, preferably a resin having a plurality of siloxane bonds (the compound and the resin are collectively referred to as “ Silicone resin "). Such a silicone resin is included in the above-mentioned (poly) siloxane compound (1). However, when the silicone resin is condensable having a hydroxyl group bonded to silicon or a hydrolyzable organic substituent, the (poly) siloxane ) It corresponds to the siloxane compound (2). The complete hydrolyzate means a product in which all hydrolyzable organic substituents are hydrolyzed, that is, tetrahydroxysilane (Si (OH) ₄ ), and the partial hydrolyzate is other hydrolyzate. (I.e., di- or trihydroxysilane). The weight average molecular weight of such a silicone resin is preferably about 200 to 2,000, and more preferably 600 to 1200.

  The silane compound (1), the (poly) siloxane compound (1), the (poly) siloxane compound (2), the tetrafunctional hydrolyzable organosilane and the silicone resin as described above are used to form a film (dry) It is preferable that the coating film becomes hydrophilic. For example, the coating film is coated on the surface of a quartz glass substrate so as to have a thickness of 100 nm, dried, and the surface water contact angle of the coating film obtained by the heat treatment at 100 ° C. is 40 ° or less. It is preferable to be able to form a film-like material having an angle of preferably 20 ° or less, more preferably 10 ° or less.

For example, silicone resin is prepared by mixing tetraalkoxysilane represented by SiX ₄ (X = OR, R is a monovalent hydrocarbon group) with a molar ratio [H ₂ O] / [OR] of 1.0 or more, for example, 1. Partial hydrolyzate and / or complete hydrolyzate obtained in the presence of water in an amount of from 0 to 5.0, preferably from 1.0 to 3.0, and preferably in the presence of an acid or alkali catalyst. It can be obtained using a hydrolyzate. In particular, a hydrolyzate and / or a complete hydrolyzate obtained by hydrolysis in the presence of an acid catalyst tends to form a two-dimensional crosslinked structure, and thus tends to increase the porosity of the dried film. When the molar ratio is less than 1.0, the amount of the unreacted alkoxyl group increases, which may adversely affect the refractive index of the coating film. There is a possibility that the coating material composition may progress rapidly and cause gelation of the coating material composition. In this case, the hydrolysis may be performed under any suitable conditions. For example, hydrolysis can be performed by stirring and mixing these materials at a temperature of 5 ° C to 30 ° C for 10 minutes to 2 hours. Further, in order to make the molecular weight 2000 or more and lower the refractive index of the matrix material itself, the obtained hydrolyzate is reacted at, for example, 40 to 100 ° C. for 2 to 100 hours to obtain a desired silicone resin. be able to.

When a silicone resin having a molecular weight of 2,000 or more is obtained as described above, a solid content in terms of SiO _{2 of} 5% by weight or more and 20% by weight or less with respect to the total amount of SiX ₄ , water, a diluted thinner and other components (contained in Six ₄ Si is used for all partial hydrolyzate obtained by hydrolysis with the amount of SiX ₄ such that SiO ₂ quantity) assuming that is converted to SiO ₂ and / or hydrolyzate Is particularly preferred. If the amount of SiX ₄ is less than 5% by weight, the amount of unreacted alkoxyl groups may increase even if the above amount of water is blended, which may adversely affect the refractive index of the matrix material, Conversely, if it is more than 20% by weight, gelling of the coating material composition may occur even if the above amount of water is blended.

  The coating material composition used in the present invention can contain various fine particles in addition to the binder component. As the fine particles, silica-based fine particles are preferably used, and when the application is to improve the transmittance, hollow fine particles, particularly hollow silica fine particles, are preferably used. Here, the hollow fine particles are particles having a cavity surrounded by an outer shell. The refractive index of the hollow fine particles themselves is preferably from 1.20 to 1.40, and more preferably from 1.20 to 1.35. The refractive index of the hollow fine particles can be measured by the method disclosed in JP-A-2001-233611. That is, Series A and AA manufactured by CARGILL are used as the standard refraction liquid, the fine particle dispersion liquid is taken in an evaporator, the dispersion medium is evaporated, and the dispersion medium is dried at 120 ° C. to obtain a powder. Next, a few drops of a standard refraction liquid having a known refractive index are dropped on a glass plate, and this powder is mixed therewith. This operation is performed using various standard refraction liquids, and the refractive index of the standard refraction liquid when the mixture becomes transparent is defined as the refractive index of the fine particles.

  Further, the preferable outer diameter of the hollow fine particles is 5 to 2000 nm, more preferably 20 to 100 nm. The outer shell may be made of any preferred material, such preferred materials include metal oxides, silica, and the like. The hollow fine particles preferably have a smaller outer shell thickness than the average particle diameter, and the volume of the hollow fine particles occupying the dry film is preferably large.

As the material constituting the outer shell of the hollow fine particles, more specifically, a single material such as SiO ₂ , SiOx, TiO ₂ , TiOx, SnO ₂ , CeO ₂ , Sb ₂ O ₅ , ITO, ATO, Al ₂ O _3, etc. Examples of the material and a mixture material obtained by combining these materials can be given. Further, a composite oxide obtained by combining any of these materials may be used. Incidentally, SiOx, when firing in an oxidizing atmosphere, which becomes a SiO ₂ are preferred. Since the dry film of the present invention has a matrix material made of a silicone resin, it is preferable to use a SiO ₂ material.

  Further, the refractive index of the hollow fine particles is preferably smaller than the refractive index of a film-like substance formed of a dry film of the matrix forming material. In this case, the difference between the two is preferably at least 0.05, more preferably at least 0.10. It is. In this case, the refractive index of the film is preferably relatively low, for example, particularly preferably 1.35 to 1.50. In another aspect, the refractive index of the hollow fine particles is preferably larger than the refractive index of the film-like material, and in this case, the difference between the two is preferably at least 0.10, and more preferably at least 0.15. Incidentally, the refractive index of the film-like material corresponds to the refractive index of the matrix portion of the dry film formed by the coating material composition used in the present invention.

  As described above, the hollow fine particles are those in which cavities are formed inside the outer shell, and any suitable known hollow fine particles may be used, but hollow fine particles particularly preferably used in the present invention are: And silica-based hollow fine particles. The average particle diameter and the refractive index are preferably as described above. Specifically, the following can be used. That is, hollow silica fine particles having a cavity inside a shell made of a silica-based inorganic oxide can be used. The silica-based inorganic oxide includes (A) a single layer of silica, (B) a single layer of a composite oxide composed of silica and an inorganic oxide other than silica, and (C) a layer of (A) and a layer of (B). And a double layer. The outer shell may be porous with pores, or the pores may be closed so that the cavity is sealed against the outside of the outer shell. The outer shell is preferably a plurality of silica-based coating layers including an inner first silica coating layer and an outer second silica coating layer. By providing the second silica coating layer on the outside, the fine pores of the outer shell can be closed to make the outer shell more dense, and further, hollow silica fine particles in which the inner cavity is sealed can be obtained.

  The thickness of the outer shell is preferably in the range of 1 to 50 nm, especially 5 to 20 nm. If the thickness of the outer shell is less than 1 nm, the hollow fine particles may not have a predetermined particle shape. Conversely, if the thickness of the outer shell exceeds 50 nm, the cavities in the hollow silica fine particles are small, and as a result, the proportion of the cavities may be reduced and the refractive index may not be sufficiently reduced. Further, the thickness of the outer shell is preferably in the range of 1/50 to 1/5 of the average particle diameter of the hollow fine particles. In the case where the first silica coating layer and the second silica coating layer are provided as outer shells as described above, the total thickness of these layers may be in the range of 1 to 50 nm, and in particular, it is densified. For the outer shell, the thickness of the second silica coating layer is preferably in the range of 20 to 49 nm.

The cavity may contain the solvent used when preparing the hollow silica fine particles and / or the gas that enters during drying. In addition, a precursor substance for forming a cavity described later may remain in the cavity. The precursor material may adhere to the outer shell and remain slightly or occupy most of the cavity. Here, the precursor substance is a porous substance remaining after removing some of the constituent components of the core particles from the core particles surrounded by the outer shell. As the core particles, porous composite oxide particles composed of silica and an inorganic oxide other than silica are used. Examples of the inorganic oxide include Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , ZnO ₂ , WO _{3 and the} like. One or more kinds can be mentioned. Examples of two or more inorganic oxides include TiO ₂ —Al ₂ O ₃ and TiO ₂ —ZrO ₂ . The solvent or gas may be present in the pores of the porous substance. At this time, when the removal amount of the constituent components of the core particles is increased, the volume of the cavity is increased, and hollow silica fine particles having a low refractive index are obtained. Excellent prevention performance.

  As described above, the average particle diameter of the hollow silica fine particles is preferably in the range of 5 nm to 2 μm (2000 nm). When the average particle diameter is smaller than 5 nm, the effect of lowering the refractive index by the hollow is small. Conversely, when the average particle diameter is larger than 2 μm, the transparency becomes extremely poor, and the contribution by diffuse reflection (anti-glare) is made. Becomes large. Applications in which a dried film formed using a coating material composition is required to have high transparency include, for example, antireflection applications such as the outermost surface of a display. For this purpose, the particle diameter of the hollow silica fine particles used is preferably in the range of 5 to 100 nm. In the present invention, the particle diameter is a number average particle diameter as observed by a transmission electron microscope.

  A method for producing hollow silica fine particles as described above is known in JP-A-2001-233611, and a product produced by this method is provided as a commercial product, and a commercial product is easily obtained and used. Can be offered.

As described above, in the coating material composition used in the present invention, one embodiment of the silicone compound is a tetrafunctional hydrolyzable organosilane represented by SiX ₄ (X is a hydrolyzable substituent), and a partial hydrolyzate thereof. And a hydrolyzate thereof, and a product obtained by condensing them (that is, a silicone resin). All of these materials are excellent in dispersion stability of hollow silica fine particles. On the other hand, when other metal oxide fine particles or organic hollow fine particles are used, the dispersion stability is lacking, and the mechanical strength of the obtained dried film tends to be inferior to that of the silica hollow fine particles. When the outermost surface of the other metal oxide or organic hollow fine particles is coated with a silica-based material, the dispersion stability and the mechanical strength of the dried film can be improved. In addition, these tetrafunctional hydrolyzable organosilanes and materials derived therefrom include trifunctional hydrolyzable organosilanes, difunctional hydrolyzable organosilanes, partial hydrolysates and hydrolysates thereof, and condensation of these silanes. As compared with the case where the resin thus obtained is used as a matrix forming material, the refractive index of the obtained film-like material can be made smaller, and the crosslink density of the dried film can be made higher.

  Examples of the above-mentioned tetrafunctional hydrolyzable organosilane include tetrafunctional alkoxysilane represented by the following formula (2).

Si (OR) ₄ Formula (2)
The “R” of the alkoxyl group “OR” in the chemical formula (2) is not particularly limited as long as it is a monovalent hydrocarbon group, but is preferably a monovalent hydrocarbon group having 1 to 8 carbon atoms. is there. For example, alkyl groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group can be exemplified. Among the alkyl groups contained in the alkoxyl group, those having 3 or more carbon atoms may be linear such as an n-propyl group, an n-butyl group, or an isopropyl group, It may have a branch such as an isobutyl group or a t-butyl group.

  In preparing a silicone resin using a tetrafunctional hydrolyzable organosilane such as a tetrafunctional alkoxysilane, the tetrafunctional hydrolyzable organosilane is hydrolyzed (hereinafter, also partially hydrolyzed) and condensed. Here, the weight-average molecular weight of the obtained silicone resin is not particularly limited, but in order to obtain a larger mechanical strength of the obtained dried film by a smaller proportion of the silicone resin in the coating material composition. The weight average molecular weight is preferably in the range of 200 to 2,000. If the weight-average molecular weight is smaller than 200, the film-forming ability may be inferior. However, in applications that do not require mechanical strength, a molecular weight of 2000 or more is effective to reduce the refractive index of the matrix material itself. The molecular weight is a numerical value measured using GPC as described later.

In general, a silicone resin obtained by hydrolyzing and condensing a tetrafunctional hydrolyzable organosilane SiX ₄ has a structure in which an unreacted group, that is, a hydrolyzable substituent X partially remains in the molecule. It is condensed and oligomerized or polymerized. When a coating is formed by coating a coating material composition, an unreacted group remains in the molecule of the silicone resin as a matrix forming material, and as a result, the formed matrix has an unreacted substituent. However, when a cured film is obtained by heat-treating a film obtained by drying at a temperature exceeding 300 ° C., unreacted groups are decomposed, which adversely affects the refractive index of the finally obtained cured film. Does not affect. When the heat treatment is performed at a relatively low temperature such as 50 to 300 ° C., particularly 50 to 150 ° C., unreacted groups may remain in the cured film without being decomposed, and as a result, as a matrix May have an adverse effect of increasing the refractive index.

  In consideration of this, the tetrafunctional hydrolyzable organosilane is used as a matrix-forming material in a state of being completely hydrolyzed than a partially hydrolyzed product, or is used as a silicone resin in a completely hydrolyzed state. And it is preferable to use it as a matrix-forming material. However, in order to completely hydrolyze, it is generally a polymer having a molecular weight of 2,000 or more, so that the mechanical strength of the dried film can be expected. And is effective for applications that do not require relatively high mechanical strength. Since the completely reacted hydrolyzate has only the -OH group at the molecular terminal, when a film is formed using this complete hydrolyzate, the remaining group is only -OH. The surface of the coating has excellent hydrophilicity, and the contact angle of the surface water droplet is small. For applications requiring mechanical strength, a silicone resin having a molecular weight of 600 to 2,000 is effective. Since the resin is a partially hydrolyzed product in this molecular weight range, the refractive index of the matrix material itself is a completely hydrolyzed silicone. Although it is larger than resin, the dry film formed from the low molecular weight condensate tends to have higher porosity, and the mechanical strength is high even if the ratio of fine particles / silicone resin condensate in the dry film is high. It is possible to keep Incidentally, with a silicone resin having a molecular weight of 2000 or more, mechanical strength cannot be expected regardless of the ratio of fine particles / silicone resin condensate.

  Specifically, in applications that do not require mechanical strength, as a silicone resin used as a matrix forming material of the coating material composition, this is applied to the surface of a quartz glass substrate so as to have a thickness of 100 nm. A cured film obtained by drying and heat-treating at 100 ° C. has a surface water contact angle of 20 ° or less, preferably 10 ° or less, more preferably 5 ° or less (substantial lower limit is 0 °). Preferably, it is used. That is, if such a silicone resin is used as a matrix-forming material, unreacted groups other than -OH do not remain even when the coating is treated at a low temperature, and the refractive index of the cured coating is easily prevented from increasing. Conversely, when using a silicone resin, the surface water droplet contact angle of which is more than 10 °, especially more than 20 °, if the coating is not heat-treated at a higher temperature, the refractive index of the cured coating becomes higher. It may be difficult to suppress the rise. In addition, the surface water droplet contact angle of a silicone resin having a molecular weight of 2000 or less does not become 20 ° or less even when the surface water droplet contact angle is measured by the method described above. This is because unreacted groups remain. The water droplet contact angle of the cured coating varies depending on the type of hollow fine particles / silicone resin used, its molecular weight and the ratio of hollow fine particles / silicone resin condensate. For example, the hollow fine particles are hollow silica fine particles, and the silicone resin is a tetrafunctional alkoxide silane. In the case of a hydrolyzate and / or a hydrolyzate, when the molecular weight of the silicone resin is 2,000 or more and the contact angle of water droplet of the dry coating of the silicone resin alone (on quartz glass) is 20 ° or less, hollow silica is used. Regardless of the ratio of the fine particles / silicone resin condensate and the drying temperature of the cured film, the surface water contact angle of the cured film is 40 ° or less. When the molecular weight of the silicone resin is 2,000 or less, if the drying temperature of the cured film is as high as 300 ° C. or more in an oxidizing atmosphere, the contact angle of the water droplet on the surface is irrespective of the ratio of the hollow silica fine particles / silicone resin condensate. When the drying temperature is as low as 300 ° C. or less, if the weight ratio of the hollow silica fine particles / silicone resin condensate is not 60/40 or more, the water droplet contact angle of the cured film becomes 40 ° or less. It tends not to be.

  In the coating material composition used in the present invention, the amount of the hollow fine particles and the amount of the matrix forming material contained in the coating material composition may be in any appropriate ratio. The ratio (that is, the weight of the hollow fine particles / the weight of the matrix forming material) is preferably 30/70 to 95/5. For example, when a tetrafunctional silicone resin is used and the molecular weight is 2,000 or more, 30/70. When the molecular weight is ６０60/40 and 2,000 or less, the ratio is more preferably from 70/30 to 90/10.

  The larger the proportion of hollow fine particles (for example, hollow silica fine particles) in the dried film, the more the refractive index of the film can be reduced, but on the other hand, the mechanical strength of the film decreases. Therefore, it is necessary to improve the mechanical strength of the coating by increasing the ratio of the hollow fine particles to a relatively small ratio of the matrix material. For this purpose, when a tetrafunctional hydrolyzable alkoxysilane or a condensable silicone resin derived therefrom is used as a matrix material, particularly when the molecular weight of the silicone resin is 2,000 or less, when forming a coating, these are condensed to form a matrix. It is preferable to improve the crosslink density when forming the polymer.

  When hydrolyzing the above-mentioned silane compound (1), particularly a tetrafunctional hydrolyzable organosilane such as a tetrafunctional alkoxysilane, in order to prepare a matrix-forming material, a catalyst may be used as necessary. The catalyst to be used is not particularly limited, but the obtained partial hydrolyzate and / or hydrolyzate is likely to have a two-dimensional crosslinked structure, and the condensed compound is easily made porous. From the viewpoint of shortening the time required, an acidic catalyst is preferable. Examples of such an acidic catalyst include, but are not particularly limited to, organic acids such as acetic acid, chloroacetic acid, citric acid, benzoic acid, dimethylmalonic acid, formic acid, propionic acid, glutaric acid, glycolic acid, maleic acid, and malonic acid. , Toluenesulfonic acid, oxalic acid, etc.), inorganic acids (eg, hydrochloric acid, nitric acid, halogenated silanes, etc.), and acidic sol-like fillers (eg, acidic colloidal silica, titania sol, etc.). The above can be used. The hydrolysis of the alkoxide may be carried out by heating, if necessary, in applications that do not require mechanical strength, and in particular, accelerates the hydrolysis reaction over 2 to 100 hours under conditions of 40 to 100 ° C. This is preferable because unreacted alkoxide groups can be reduced as much as possible, and the refractive index of the matrix forming material itself is reduced. If the hydrolysis is performed outside the above temperature range or time range, unreacted alkoxide groups may remain. Incidentally, instead of the acidic catalyst, sodium hydroxide, an aqueous solution of an alkali metal or alkaline earth metal hydroxide such as calcium hydroxide, aqueous ammonia, an alkaline catalyst such as an aqueous solution of amines may be used, An acidic catalyst is preferable in the point that an alkaline catalyst easily forms three-dimensional crosslinks, lowers the porosity of a dried film, and easily gelates. When the matrix-forming material has a hydrolyzable substituent, the matrix-forming material may contain a hydrolysis catalyst.

  The coating material composition used in the present invention is prepared by containing the above-mentioned fine particles, preferably a hollow silica fine particle, and a silicone compound composed of the above-mentioned matrix-forming material. It is also preferred to include water or a mixture of water and another liquid, such as an organic solvent, in that at least partial hydrolysis of the matrix-forming material may preferably occur. Examples of the organic solvent include lower aliphatic alcohols such as methanol, ethanol, isopropanol (IPA), n-butanol, isobutanol, ethylene glycol derivatives such as ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether acetate; and diethylene glycol. And diethylene glycol derivatives such as diethylene glycol monobutyl ether; and hydrophilic organic solvents such as diacetone alcohol. One or more selected from the group consisting of these can be used. Further, one or more of toluene, xylene, hexane, heptane, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like may be used in combination with these hydrophilic organic solvents. it can.

In the coating material composition used in the present invention, the matrix forming material can be classified into the following three embodiments (a), (b) and (c):
(A) In one embodiment, the matrix forming material is the silane compound (1) described above (preferably a tetrafunctional hydrolyzable organosilane, more preferably a tetrafunctional hydrolyzable alkoxysilane). In this case, the silane compound (1) is added in the presence of water during the preparation and coating of the coating material composition by mixing and mixing the constituent components, and / or during the coating of the base film after preparation and drying of the coating film. To form a matrix.

  (B) In another aspect, the matrix forming material is a (poly) siloxane compound (2), preferably a condensable silicone resin. In this case, the (poly) siloxane compound (2) is condensed in the presence of water during the preparation of the coating material composition and / or during the coating of the base film after the preparation and drying of the coating film, thereby forming a matrix. To form In addition, the degree to which the condensation occurs is smaller than the above-described embodiment in which the silane compound (1) is included as the matrix forming material.

  (C) In yet another aspect, the matrix-forming material is a (poly) siloxane compound (1), preferably a silicone resin, wherein the compound has substantially no hydroxyl groups or hydrolyzable substituents. Compound. In this case, the (poly) siloxane compound (1) forms a porous matrix without condensation during the preparation of the coating material composition and during the coating of the base film and the drying of the coating film after the preparation.

  The dried film obtained by the above coating material composition has hollow fine particles and a porous matrix, and the porosity thereof is in the range of 10 to 95%, preferably 30 to 80%, more preferably 40 to 60%. . When the porosity is particularly large, a dried film having a particularly low refractive index can be formed. When preparing the coating material composition, the porosity in the above range can be achieved by variously changing the formulations of the hollow fine particles and the matrix forming material to be blended. Here, the porosity can be determined as follows. That is, the element species and the average element ratio present as a solid in the dried film are measured by XPS (X-ray photoelectron spectroscopy), and the density (ds) of the solid part is calculated from the ratio (no hydrogen is detected). However, the atomic weight is so small that it is ignored.) In addition, the thickness of the dried film is measured with an ellipsometer, and the weight of the dried film and the weight of the substrate on which the dried film is formed are measured before and after the formation. The size is about 300 mm square, and the thickness of the formed film is preferably about 1 μm), the density (df) of the dried film, and the volume (Vf) of the dried film are calculated. The porosity is calculated from the following equation.

ds × Vf × (1−porosity / 100) = df × Vf
The porosity can be changed by adding other components as needed.

  The coating material composition used in the present invention may contain non-hollow fine particles, for example, non-hollow fine silica particles (hereinafter, simply referred to as silica particles). By coexisting such fine particles, the mechanical strength of the formed dried film can be improved, and further, the surface smoothness and crack resistance of the film can be improved.

  The form of the silica particles is not particularly limited, and may be, for example, a powder form or a sol form. When the silica particles are used in the form of a sol, that is, as colloidal silica, there is no particular limitation.For example, water-dispersed colloidal silica or colloidal silica dispersed in a hydrophilic organic solvent such as alcohol may be used. it can. Generally, such colloidal silica contains 20 to 50% by weight of silica as a solid content, and the amount of silica can be determined from this value.

  Here, when water-dispersed colloidal silica is used, water present in the colloidal silica as a component other than solids may be used for hydrolysis of the silane compound (1), for example, a tetrafunctional hydrolyzable organosilane. it can. Therefore, it is necessary to add water of water-dispersed colloidal silica to the amount of water at the time of this hydrolysis. The water-dispersed colloidal silica is usually made of water glass, and a commercially available product can be easily obtained and used.

  The organic solvent-dispersed colloidal silica can be easily prepared by substituting the water of the water-dispersed colloidal silica with an organic solvent. Such an organic solvent-dispersed colloidal silica can be easily obtained and used as a commercial product, similarly to the water-dispersed colloidal silica. In the organic solvent-dispersed colloidal silica, the type of the organic solvent in which the colloidal silica is dispersed is not particularly limited. For example, lower fats such as methanol, ethanol, isopropanol (IPA), n-butanol, and isobutanol are used. Aromatic alcohols, ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol derivatives such as ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol derivatives such as diethylene glycol monobutyl ether, and hydrophilic organic solvents such as diacetone alcohol, One or more selected from the group consisting of these can be used. Furthermore, one or more of toluene, xylene, hexane, ethyl heptane acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like can be used in combination with these hydrophilic organic solvents. .

  The amount of the solid fine particles, for example, the above-mentioned silica particles, is preferably 0.1 to 30% by weight based on the total solid content in the coating material composition. If the amount is less than 0.1% by weight, the effect of the addition of the silica particles may not be obtained. If the amount exceeds 30% by weight, the mechanical strength of the dried film may be adversely affected.

  Since the dried film formed by the above coating material composition is a film having a low refractive index, the film may be colored. In this case, it is preferable that a coloring compound is previously contained in the coating material composition to adjust the color of the film. The dye compound is not particularly limited, such as inorganic or organic, and a commercially available compound may be added in an appropriate amount so as to obtain a desired color tone within a range that does not significantly affect the refractive index of the film. Further, a leveling material and a viscosity modifier can be added to the coating material composition as needed.

  In addition, the coating material composition obtained as described above may be diluted with an organic solvent or water as necessary, as described above, and in preparing the coating material composition, the individual components are previously prepared. May be diluted with an organic solvent, water or the like as necessary. The organic solvent used for the dilution is not particularly limited, and for example, lower aliphatic alcohols such as methanol, ethanol, isopropanol (IPA), n-butanol and isobutanol; ethylene glycol, ethylene glycol monobutyl ether And ethylene glycol derivatives such as ethylene glycol monoethyl ether acetate; diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; and diacetone alcohol. One or more selected from the group consisting of these are used. be able to. Furthermore, one or more of toluene, xylene, hexane, ethyl heptane acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like can be used in combination with these hydrophilic organic solvents. .

  Then, the coating material composition prepared as described above is coated on the surface of the fluorine-based resin film substrate to form a coating film, and a dried coating film can be obtained by drying and curing the coating film. And a fluorine-based composite resin film having a transparent resin layer having a low refractive index formed on the outermost surface. The transparent resin layer on the outermost surface formed by this dried film has a hydrophilic property with a surface water droplet contact angle of 40 ° or less (the smaller the surface contact angle, the better, ideally 0 °). The adhered dirt is easily washed away with rainwater or the like, and is formed to have a surface antifouling property. Therefore, a surface antifouling article can be obtained by attaching this fluorine-based composite resin film to the surface of the article by heat sealing, bonding with an adhesive, or bonding with an adhesive. . Further, when the transparent resin layer is formed in a plurality of layers, the transparent resin layer on the outermost surface may be formed to have a lower refractive index than the transparent resin layer therebelow to prevent reflection and improve transmittance. Is necessary.

  Here, in the present invention, a film in which a transparent acrylic resin film is laminated on a transparent fluorine-based resin film is used as the fluorine-based resin film substrate. Since the refractive index of the fluororesin film alone is in the range of 1.34 to 1.40, in order to improve the transmittance, the dry film formed by the present invention needs to have a refractive index of 1.30 or less. Is done. On the other hand, since the refractive index of the acrylic resin film is 1.47 or higher, which is higher than that of the fluororesin film, when the acrylic resin film is laminated on the fluororesin film in this way, it is necessary to improve the transmittance. The dry film formed by the present invention has a refractive index of 1.44 or less, which is lower than the refractive index of the acrylic resin film, so that the degree of freedom in designing a coating material composition for forming the dry film can be increased. It is.

  The fluorine-based resin film is not particularly limited, but may be a polytetrafluoroethylene resin (PTFE), a polyvinylidene fluoride resin (PVdF), a polyvinyl fluoride resin (PVF), or a copolymer containing fluorine. Resins, for example, copolymers comprising two or more monomers selected from the group consisting of ethylene difluoride, ethylene trifluoride, ethylene trifluoride chloride, ethylene tetrafluoride, propylene hexafluoride, fluoroalkyl vinyl ether and ethylene Coalescing resin, specifically, PFA (perfluoroalkoxyalkane), PFEP (perfluoroethylene propene copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), PCTFE (polychlorotrifluoroethylene), ECTFE (ethylene-chlorotriene) Fluoroethyl Nko polymer), TFE-FEP, TFE-PVdF, TFE-FEP-PVdF or the like, can be preferably used at least one selected from.

  Further, at least one or more other transparent resin layers may be formed on the surface of the fluororesin film substrate in advance. For example, examples of the other transparent resin layer include an ultraviolet curable hard coat layer, an electron beam curable hard coat layer, and a thermosetting hard coat layer. Among these, a thermosetting hard coat layer is preferable in consideration of durability outdoors. The material of the hard coat layer is roughly classified into an organic resin mainly composed of an acrylic resin and a urethane resin, and a silicone resin. By adding an ultraviolet absorber to this hard coat layer, it is possible to impart an ultraviolet absorption function.

Further, it is also possible to add inorganic particles having a large particle diameter (0.3 μm or more) to the transparent resin layer forming the hard coat layer to impart the function of the light diffusion layer. The light diffusion layer is particularly important when the fluorine-based composite resin film of the present invention is adhered to the surface of a solar cell module and used as a protective film for a solar cell. The reflected light on the solar cell module can be directed to the surface of the solar cell module again from the light diffusion layer without escaping the reflected light as much as possible, thereby increasing the power generation efficiency. At this time, if an inorganic ultraviolet absorber represented by a metal oxide such as ZnO or CeO ₂ is selected as the inorganic particles, it is possible to simultaneously provide the light diffusion layer with an ultraviolet absorption function and a light diffusion function. The refractive index of the transparent resin layer forming the hard coat layer may be appropriately selected and adjusted according to the refractive index of the transparent resin layer formed of the above-mentioned dried film formed thereon. Needless to say, the same function as described above can be provided by adding an ultraviolet absorber and particles having a large particle diameter to the fluororesin film base material.

  Incidentally, when coating the coating material composition on the surface of the fluororesin film substrate, so that the coating is formed uniformly, or so as to improve the adhesion between the coating and the fluororesin film substrate, It is preferable to pre-clean the surface of the fluororesin film substrate (or the surface of the transparent resin layer if the transparent resin layer is provided in advance). Examples of the pre-cleaning method include alkali cleaning, ammonium fluoride cleaning, plasma cleaning (including reduced pressure plasma and atmospheric pressure plasma), UV ozone cleaning, cerium oxide cleaning, and cleaning by corona discharge.

  The method for coating the surface of the fluororesin film substrate with the coating material composition is not particularly limited, and examples thereof include brush coating, spray coating, dipping (dip coating), roll coating, and gravure. Coating, microgravure coating, flow coating, curtain coating, knife coating, spin coating, table coating, sheet coating, single-wafer coating, die coating, bar coating, reverse coating, cap coating, etc. it can. When a coating is formed by a coating method using a coating material composition as described above, a coating having a larger area can be easily obtained than in a gas phase method or a liquid phase method, and a film can be formed at a high speed. You can do it.

  Then, it is preferable to perform a heat treatment on the film formed by coating the surface of the fluororesin film substrate with the coating material composition as described above, and then drying the film. By this heat treatment, the mechanical strength of the coating can be further improved. The temperature at the time of the heat treatment is not particularly limited. By performing the heat treatment in this manner, the hardness of the film can be increased, and the film after the heat treatment can be formed into a hardened coating.

  For example, when a coating is formed using a coating material composition using a silicone resin formed from a tetrafunctional alkoxy resin as a matrix forming material, the coating is formed at a low temperature, preferably at 100 to 300 ° C, more preferably at 50 to 150 ° C for 5 to 30 ° C. Perform a partial heat treatment. Even if the heat treatment is performed at a low temperature in this manner, it is possible to obtain substantially the same mechanical strength as in the case of performing the heat treatment at a high temperature, and in this case, it is possible to reduce the cost of forming a coating film . In addition, unlike the case of heat treatment at a high temperature, the type of the base film is not limited.

  Further, the thickness of the dried film (the outermost transparent resin layer) formed on the fluororesin film substrate can be appropriately selected depending on the intended use, purpose, and the like, and is not particularly limited. The range is preferably 0.01 to 10.0 μm, and more preferably 0.01 to 0.5 μm in order to suppress the occurrence of cracks in the dried film.

  Hereinafter, the present invention will be described specifically with reference to examples. Unless otherwise specified, all “parts” represent “parts by weight”, and “%” represents “% by weight” except for the total light transmittance and the haze ratio described later. The weight molecular weight was measured by GPC (gel permeation chromatography) using a standard polystyrene calibration curve using "HLC8020" manufactured by Tosoh Corporation as a measuring instrument, and the converted value was measured.

<Example 1>
To 208 parts of tetraethoxysilane, 356 parts of methanol is added, and 126 parts of water and 18 parts of 0.01N hydrochloric acid (“H ₂ O” / “OR” = 2.0) are added, and these are mixed well using a disper. Thus, a mixed solution was obtained. This mixture was stirred in a thermostat at 25 ° C. for 2 hours, and the weight average molecular weight was adjusted to 4000 to obtain a silicone resin (A). Next, silica fine particles (trade name: OSCAL1432, “IPA-dispersed colloidal silica”, manufactured by Catalyst Kasei Kogyo Co., Ltd., primary particle diameter: 10 to 20 nm, solid content 30%) were added to the silicone resin (A). ) (In terms of condensed compound) was blended so that the weight ratio was 40/60 based on the solid content, and then diluted with IPA so that the total solid content was 1%, to prepare a coating material composition. .

  Then, after leaving this coating material composition for 1 hour, a PVdF / acryl composite film (manufactured by Kureha Chemical Industry Co., Ltd., trade name: Kureha KFC film, product number: FT-50Y, PVdF thickness: 4 μm, acrylic thickness: 46 μm, total film) A 50 μm thick, PVdF refractive index: 1.42, acrylic refractive index: 1.47) was coated on an acrylic surface with a wire bar coater to form a coating film having a thickness of about 100 nm, which was left for 1 minute. After drying, the dried film was heat-treated at 80 ° C. for 10 minutes in an oxygen atmosphere to obtain a fluorine-based composite resin film.

<Example 2>
To 208 parts of tetraethoxysilane, 356 parts of methanol is added, and 126 parts of water and 18 parts of 0.01N hydrochloric acid (“H ₂ O” / “OR” = 2.0) are further mixed. The mixture was obtained by mixing. This mixture was stirred in a constant temperature bath at 25 ° C. for 2 hours and heated in a constant temperature bath at 60 ° C. for 20 hours to adjust the weight average molecular weight to 6,000, thereby obtaining a silicone resin (B). Next, silica fine particles (trade name: OSCAL1432, “IPA-dispersed colloidal silica”, primary particle diameter: 10 to 20 nm, solid content: 30%) manufactured by Catalyst Kasei Kogyo Co., Ltd. were added to the silicone resin (B). ) (In terms of condensed compound) was blended so that the weight ratio was 40/60 based on the solid content, and then diluted with IPA so that the total solid content was 1%, to prepare a coating material composition. .

  After leaving this coating material composition for 1 hour, a PVdF / acryl composite film (Kureha Chemical Industry Co., Ltd., trade name: Kureha KFC film, product number: FT-50Y, PVdF thickness: 4 μm, acrylic thickness: 46 μm, total film) A 50 μm thick, PVdF refractive index: 1.42, acrylic refractive index: 1.47) was coated on an acrylic surface with a wire bar coater to form a coating film having a thickness of about 100 nm, which was left for 1 minute. After drying, the dried film was heat-treated at 80 ° C. for 10 minutes in an oxygen atmosphere to obtain a fluorine-based composite resin film.

<Example 3>
In Example 2, the silica fine particles were changed to hollow silica fine particles (trade name: CS-60IPA “IPA-dispersed colloidal hollow silica”, manufactured by Catalyst Chemical Industry, primary particle diameter: about 60 nm, outer shell thickness: about 15 nm, solid content: 20%). A fluorine-based composite resin film was obtained in the same manner as in Example 2 except for performing the above.

<Example 4>
To 208 parts of tetraethoxysilane, 356 parts of methanol is added, and 18 parts of water and 18 parts of a 0.01 N hydrochloric acid aqueous solution (“H ₂ O” / “OR” = 0.5) are added. The mixture was obtained by mixing. The mixture was stirred in a thermostat at 25 ° C. for 2 hours to obtain a silicone resin (C) whose weight average molecular weight was adjusted to 850. Next, silica fine particles (trade name: OSCAL1432, “IPA-dispersed colloidal silica”, manufactured by Catalyst Kasei Kogyo Co., Ltd., primary particle diameter: 10 to 20 nm, solid content 30%) were mixed with the silicone resin (C). ) (Condensed compound equivalent) was blended so that the weight ratio was 80/20 on the solid content basis, and then diluted with IPA so that the total solid content was 1%, to prepare a coating material composition. .

  After leaving this coating material composition for 1 hour, a PVdF / acryl composite film (Kureha Chemical Industry Co., Ltd., trade name: Kureha KFC film, product number: FT-50Y, PVdF thickness: 4 μm, acrylic thickness: 46 μm, total film) A 50 μm thick, PVdF refractive index: 1.42, acrylic refractive index: 1.47) was coated on an acrylic surface with a wire bar coater to form a coating film having a thickness of about 100 nm, which was left for 1 minute. After drying, the dried film was heat-treated at 80 ° C. for 10 minutes in an oxygen atmosphere to obtain a fluorine-based composite resin film.

<Example 5>
In Example 4, the silica fine particles were changed to hollow silica fine particles (trade name: CS-60IPA “IPA-dispersed colloidal hollow silica”, manufactured by Catalyst Chemical Industry, primary particle diameter: about 60 nm, outer shell thickness: about 15 nm, solid content: 20%). A fluorine-based composite resin film was obtained in the same manner as in Example 4 except for performing the above.

<Example 6>
Fine particles of zinc oxide (manufactured by Matsushita Electric Works, trade name: Fresella N-A210, solid content: 20%) are coated with zinc oxide fine particles (manufactured by Sumitomo Osaka Cement, primary particle diameter: 0.2 μm), and silicone-based coating material (condensation compound) The silicone-based coating material composition was prepared by adding the fine particles / zinc oxide in a weight ratio of 80/20. Then, this silicone-based coating material composition is applied on the acrylic surface of the PVdF / acryl composite film by a wire bar coater to form a coating film having a thickness of about 5 μm. Heat treatment was performed at 60 ° C. for 60 minutes in an oxygen atmosphere to form a transparent silicone-based thermosetting hard coat resin layer. A fluorine-based composite resin film was obtained in the same manner as in Example 2, except that the composite film on which the silicone-based thermosetting hard coat resin layer was formed was used.

<Comparative Example 1>
PVdF / acrylic composite film (manufactured by Kureha Chemical Industry, trade name: Kureha KFC film, product number: FT-50Y, PVdF thickness: 4 μm, acrylic thickness: 46 μm, total film thickness: 50 μm, PVdF refractive index: 1.42, acrylic refraction) Rate: 1.47) was used without any coating and was used as Comparative Example 1.

<Comparative Example 2>
Example 5 was carried out in the same manner as in Example 5 except that the hollow silica fine particles / silicone resin (C) (condensed compound equivalent) were blended so that the weight ratio was 50/50 based on the solid content.

<Comparative Example 3>
To 178 parts of methyltriethoxysilane, 356 parts of methanol is added, and 90 parts of water and 18 parts of 0.01N hydrochloric acid (“H ₂ O” / “OR” = 2.0) are further mixed. Mix well to obtain a mixture. This mixture was stirred for 2 hours in a thermostat at 25 ° C., and the weight average molecular weight was adjusted to 800 to obtain a silicone resin (D). And it carried out similarly to Example 1 except having used this silicone resin (D).

  For the composite resin films obtained in Examples 1 to 6 and Comparative Examples 1 to 3, the total light transmittance, the haze, the refractive index of the dried film on the surface, the contact angle of water droplets, and the stain resistance were measured, and the composite resin was measured. The performance of the film was evaluated.

(Total light transmittance)
The total light transmittance at a wavelength of 550 nm was measured using a spectrophotometer (“U-3400” manufactured by Hitachi, Ltd.).

(Haze rate)
It was measured using a haze meter ("NDH2000" manufactured by Nippon Denshoku Industries Co., Ltd.).

(Refractive index)
After observing the fracture surface of the film with a scanning electron microscope and measuring the film thickness of the dried film, the refractive index was derived with an ellipsometer (“EMS-1” manufactured by ULVAC).

(Contact angle)
It measured using the contact angle meter ("CA-W150" by Kyowa Interface Science).

(Stain resistance)
The composite film was placed outdoors (on the building rooftop of Kadoma 1048, Kadoma-shi, Osaka, Matsushita Electric Works) at a south direction and a tilt angle of 30 °, and after being exposed for half a year, the total light transmittance was measured.

  Table 1 shows the test results.

  As can be seen from the results in Table 1, the light transmittance of each of the examples was higher than that of Comparative Example 1 in which a dry film of the coating material composition was not formed and Comparative Examples 2 and 3 in which the contact angle of the dry film was large. It has been confirmed that can be maintained for a long time outdoors.

Claims (6)

  A fluorine-based composite resin formed by laminating an acrylic film having a higher refractive index than the fluorine-based film on the surface of the transparent fluorine-based film and laminating one or more transparent resin layers on the surface of the acrylic-based film In the film, the outermost transparent resin layer is formed of a coating dry film having a condensate of a silicone compound as a binder component and having a surface water contact angle of 40 ° or less, and the refractive index of the outermost dry film. Is a fluorine-based composite resin film having a refractive index lower than that of a transparent resin layer or an acrylic film located immediately below.   The fluorine-based composite resin film according to claim 1, wherein the transparent resin layer immediately below the outermost dried film is a thermosetting hard coat resin layer.   3. The fluorine-based composite resin film according to claim 1, wherein at least a part of the transparent resin layer is formed to have a light diffusing means.   The fluorine-based composite resin film according to claim 3, wherein the light diffusion means is formed of inorganic particles having an ultraviolet absorbing function.   The fluorine-based composite resin film according to claim 4, wherein the inorganic particles are a metal oxide.   A solar cell, wherein the fluorine-based composite resin film according to claim 1 is provided on an outermost surface of a solar cell module.